Ground Testing A 20-Meter Inflation Deployed Solar Sail

Solar sails have been proposed for a variety of future space exploration missions and provide a cost effective source of propellantless propulsion. Solar sails span very large areas to capture and reflect photons from the Sun and are propelled through space by the transfer of momentum from the photons to the solar sail. The thrust of a solar sail, though small, is continuous and acts for the life of the mission without the need for propellant. Recent advances in materials and ultra-low mass gossamer structures have enabled a host of useful space exploration missions utilizing solar sail propulsion. The team of L Garde, NASA Jet Propulsion Laboratory (JPL), Ball Aerospace, and NASA Langley Research Center, under the direction of the NASA In-Space Propulsion Office (ISP), has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. The 100-m baseline solar sail concept was optimized around the one astronomical unit (AU) Geostorm mission, and features a Mylar sail membrane with a striped-net sail suspension architecture with inflation-deployed sail support beams consisting of inflatable sub-Tg (glass transition temperature) rigidizable semi-monocoque booms and a spreader system. The solar sail has vanes integrated onto the tips of the support beams to provide full 3-axis control of the solar sail. This same structural concept can be scaled to meet the requirements of a number of other NASA missions. Static and dynamic testing of a 20m scaled version of this solar sail concept have been completed in the Space Power Facility (SPF) at the NASA Glenn Plum Brook facility under vacuum and thermal conditions simulating the operation of a solar sail in space. This paper details the lessons learned from these and other similar ground based tests of gossamer structures during the three year solar sail project

Structural Analysis and Test Comparison of a 20-Meter Inflation-Deployed Solar Sail

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive test program was implemented to advance the technology readiness level of the solar sail design. These tests consisted of solar sail component, subsystem, and sub-scale system ground tests that simulated the aspects of the space environment such as vacuum and thermal conditions. In July 2005, a 20-m four-quadrant solar sail system test article was tested in the NASA Glenn Research Center s Space Power Facility to measure its static and dynamic structural responses. Key to the maturation of solar sail technology is the development of validated finite element analysis (FEA) models that can be used for design and analysis of solar sails. A major objective of the program was to utilize the test data to validate the FEA models simulating the solar sail ground tests. The FEA software, ABAQUS, was used to perform the structural analyses to simulate the ground tests performed on the 20-m solar sail test article. This paper presents the details of the FEA modeling, the structural analyses simulating the ground tests, and a comparison of the pretest and post-test analysis predictions with the ground test results for the 20-m solar sail system test article. The structural responses that are compared in the paper include load-deflection curves and natural frequencies for the beam structural assembly and static shape, natural frequencies, and mode shapes for the solar sail membrane. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were unmeasured initial conditions in the test set-up

Structural Analysis of an Inflation-Deployed Solar Sail With Experimental Validation

Under the direction of the NASA In-Space Propulsion Technology Office, the team of L Garde, NASA Jet Propulsion Laboratory, Ball Aerospace, and NASA Langley Research Center has been developing a scalable solar sail configuration to address NASA s future space propulsion needs. Prior to a flight experiment of a full-scale solar sail, a comprehensive phased test plan is currently being implemented to advance the technology readiness level of the solar sail design. These tests consist of solar sail component, subsystem, and sub-scale system ground tests that simulate the vacuum and thermal conditions of the space environment. Recently, two solar sail test articles, a 7.4-m beam assembly subsystem test article and a 10-m four-quadrant solar sail system test article, were tested in vacuum conditions with a gravity-offload system to mitigate the effects of gravity. This paper presents the structural analyses simulating the ground tests and the correlation of the analyses with the test results. For programmatic risk reduction, a two-prong analysis approach was undertaken in which two separate teams independently developed computational models of the solar sail test articles using the finite element analysis software packages: NEiNastran and ABAQUS. This paper compares the pre-test and post-test analysis predictions from both software packages with the test data including load-deflection curves from static load tests, and vibration frequencies and mode shapes from structural dynamics tests. The analysis predictions were in reasonable agreement with the test data. Factors that precluded better correlation of the analyses and the tests were uncertainties in the material properties, test conditions, and modeling assumptions used in the analyses

Sunjammer: A Solar Sail Demonstration

No abstract availabl

Health Outcomes from Aggregate Particulate Matter

https://louis.uah.edu/rceu-hcr/1072/thumbnail.jp

Superfield approach to the spontaneous breakdown of local supersymmetry

The goal of this thesis is to obtain a superfield formulation of local supersymmetry, and to construct via this formalism a model of spontaneous local supersymmetry breakdown. In the first chapter, the superfield method and some globally supersymmetric models are reviewed. These include Lagrangians for massive interacting chiral multiplets, and models for both massive and massless vector multiplets. In particular, the globally supersymmetric extension of the Higgs mechanism, due to Fayet, is described in detail. This model will form the basis of a locally supersymmetric model incorporating spontaneous supersymmetry breakdown in the third chapter. None of this work is original. The second chapter is devoted to gauging supersymmetry without superfields . The earliest supergravity theories (those not involving matter coupling) are reviewed. The fiber bundle approach is described, and shown to be ambiguous. An alternative algebraic scheme for dealing with gravi¬ tational symmetries is given. Superfield supergravity in two dimensions forms the subject matter of the third chapter. A brief glimpse of a one-dimensional locally supersym¬ metric theory (the spinning particle) is given. Its two-dimensional analogue, the spinning string, is obtained first without recourse to superfields, and then via an elegant superfield Ansatz due to Howe. It is shown how to derive this Ansatz and its transformation. Finally, a locally supersymmetric version of the Fayet model is given. The generalised Higgs mechanism works to remove the Goldstone spinor, but via a gauge field (the gravitino) which is forced to be non-dynamical in two dimensions. The methods of the third chapter are extended to four dimensions in the fourth chapter. The corresponding vielbein is derived, and shown not to transform covariantly without the addition of new terms. An attempt is made to find these terms, and it is argued that no additions can render the vielbein covariant. Consequently the approach of the third chapter proves inapplicable to four dimensions, and no matter-supergravity coupling can be obtained in this way. Three appendices on the history of anticommuting variables, the use of differential forms, and on some useful identities, complete the thesis

Quantum mechanics emerges from information theory applied to causal horizons

It is suggested that quantum mechanics is not fundamental but emerges from classical information theory applied to causal horizons. The path integral quantization and quantum randomness can be derived by considering information loss of fields or particles crossing Rindler horizons for accelerating observers. This implies that information is one of the fundamental roots of all physical phenomena. The connection between this theory and Verlinde's entropic gravity theory is also investigated.Comment: REvtex4-1, 6pages, 2 figures, final versio

Tulane University Office of Development

As an intern with the Development Department, I served as support for Julianne Nice, Assistant Vice President for University Program Development and interim Director of Major Gifts